Davit



Sept. 19, 1939. v. KRzEMlNsKY DAVIT 2 Sheets-Sheet 2 Filed Oct. l0, 1958 em zhJ/l/ f y??? my Patented Sept. 19, 1939 lmuffin) STATES DAVIT Valentin Krzeminsky, Schiedam, Netherlands, assignor to Ane Pieter Schat, Utrecht, Netherlands Application october 1o, 193s, serial No. 234,279 In the Netherlands December 10, 1936 This invention relates to' davits of the known type comprising a substantially vertical four bar linkage having a xed lower` outside hinge and a xed lower inside hinge both suitably secured to the deck, upwardly extending outside and inside bars rotatable about said fixed lower hinges, respectively, and a suspension point for the boat, said suspension point being supported from an upper bar connecting the upper outside and the upper inside hinges respectively associated with said upwardly extending bars.

The invention, which has for its purpose to improve davits of the aforesaid type, consists herein that during movement of the four bar linkage from inboard to outboard position (assuming the ship to be substantially horizontal), the upper bar swings through an angle not smaller than the angle described by the outside bar, that the suspension point is located below the upper hinge of the outside bar, and that the suspension point and the outside bar are situated, in the inboard as well as in the outboard position of the davit, on opposite sides of a perpendicular extending through the upper hinge of the outside bar.

Other features of the invention will be described with reference to the annexed, more or less diagrammatic drawings.

In the drawings: Figure 1 is an end elevational View of the davit. Figure 2 is a similar view illustrating a modified construction.

In Fig. l, a suitable davit bracket 6 is secured to the deck 5 of the ship. Upwardly extending 3 outside and inside bars I and 3 are hinged to said bracket as at I4 and 32. An upper bar 2 is hinged, as at 'I and 34, to the upper ends of bars I and 3, respectively. Rigidly secured to bar 2 is an arm 8, the free end of which forms the aforesaid suspension point 33 of the boat.

The davit is adapted to be operated by means of a screw spindle 9 cooperating with female thread of a sleeve 3l, said spindle and sleeve being hinged to the bracket 5 and to the central 45 portion of bar I, respectively. The screw spindle 9 is operatively connected with a crank handle, by means of which it can'be turned in the one or the other direction so as to move the davit towards its inboard or its outboard position. These 5 positions are shown in full lines and in dotted lines, respectively.

With the construction shown in Fig. 1, the two davits of each set are to be spaced a distance exceeding the length of the boat to be handled thereby, seeing that the arm 8 during its swinging movement passes the bar I and cannot, therefore, be situated in the plane of movement of said bar. Fig. 2, however, illustrates a davit adapted to be placed inside the corresponding end of the boat. The bar or davit arm I here is curved,

so that the suspension point 33 during its movement does not pass said bar. Consequently, all lbars may be arrangedto be situated in the plane of movement ofvbar I.l

My novel davit has the following advantageous Y features as compared with known constructions of the type referred to:

(a) The four bar linkage l, I4, 32, 34 allows the bar 2 to swing through a considerable anguiar distance during its movement from its one to its other extreme position,

(b) The suspension point 33, which is located below the hinge '1, and the bar I are always situated on opposite sides of the perpendicular through hinge 1.

The feature (h) also implies that the arm 8 always ponts downwards.

Owing to said features, the following results are obtained:

I. The great angular movement of bar 2 is transmitted, owing to the substantially vertical position of arm B, into a horizontal displacement of suspension point 33 through a maximum distance. If the arm 8 were substantially horizontal and directed to the left, as is the case in the prior construction, rotation of bar 2 about the hinge 'I would not result in any appreciable horizontal displacement of point 33.

The aforesaid transmission of the angular movement of bar 2 into a horizontal displacement of point 33 through a great distance has the following advantages over said prior construction:

(1) The distance 1 33 may be decreased, so that the forces acting on bars I and 3 will be reduced.

(2) The distance 33-33, through which the boat is swung outwards, is increased.

(3) The angular distance through which the davit is movable may be relatively small, owing whereto (a) The length of the screw spindle 9 may be reduced, so that the swinging out of the boat requires less tima-and (b) The four bar linkage need not assume unfavourable positions, so that the forces acting on the bars I and 3 never exceed a low limit.

(4) The weight of the davit arm I and, consequently, of the whole davit is reduced.

(5) Owing to the increased inboard movement of the suspension point 33 relative to the hinge I4, said hinge may be situated at or quite near to the ships side.

II. Since the suspension point 33 and the arm I are always situated on opposite sides of the perpendicular passing through hinge 1, theupward movement of point 33 incident upon swinging movement of bar l, is compensated by the downward movement incident upon rotation of arm 8, and vice versa, so that the boat moves through a substantially horizontal path. Consequently, the operation of the davit does not require any appreciable amount of energy, and the davit is practically in equilibrium in any of its positions. This means, that the screw spindle is always substantially relieved of load.

III. 'I'he point 33 is always situated more or less vertically below the hinge '1. Also owing thereto, the moment of the load relative to the hinge 1, and consequently the forces acting on the bars l and 3 are small.

What I claim is:

In combination with the deck of a ship, a davit comprising an outside bar and an inside bar both hinged at the lower ends to the deck, a top link hingedly interconnecting the upper ends of said bars, boat suspension means secured to said top link and situated on a level lower than the upper end of said outside bar, means for imparting limited swinging movement to said davit from an inboard to an outboard position and from an outboard to an inboard position, the

' lower hinge of the inside bar being situated at a substantial distance inwardly of the lower hinge of the outside bar, the angle formed by straight lines interconnecting the upper ends of said bars in their inboard and outboard positions exceeding the angle formed by the straight lines connecting the lower and the upper hinges of the outside bar in the inboard and outboard position of said outside bar, and said boat suspension means being situated in the inboard and in the outboard position at opposite sides of the vertical through the upper hinge of the outside bar. VALENTIN KRZEMINSKY. 

